A running tire supports a vehicle body while carrying out a rotation. In the tire, a deformation and a restoration are repeated alternately. The repetition of the deformation and the restoration causes a generation of heat over the tire.
In respect of the fact that a vehicle can run continuously by a certain distance at a high speed in a puncture, a run flat tire having a reinforcing rubber layer provided in a sidewall portion is disclosed in Japanese Laid-Open Patent Publication No. 2007-50854. In the sidewall portion of the run flat tire, there is provided a plurality of radiating groove-shaped portions which can effectively dissipate heat stored in the reinforcing rubber layer in a running operation in a puncture state.    Patent Document 1: Japanese Laid-Open Patent Publication No. 2007-50854